Operator Troubleshooting
D–2
1503C MTDR User Manual
Relationships
Z
O
= (138 /
p
κ
)*
(log
10
D / d) for coaxial cable
%
=
*
100
VSWR = (1 +
) + (1 –
) for the case where VSWR is the same for all frequencies
c
= 30 cm / nanosecond = 0.984 ft / ns
V
F
= 1 /
p
κ
V
P
= 30 /
p
κ
cm / ns = 0.984 /
p
κ
ft /ns
C
= 7.36
κ
+ (log
10
D / d)
L
= 140 log
10
D / d
1 in
= 2.54 cm
1 ft
= 30.48 cm
1 m
= 3.28 ft
VSWR vs. Percent Reflected Voltage
To find the Voltage Standing Wave Ratio (VSWR), knowing the percent reflected
voltage (%), or vice versa, use the Frequency Domain Conversions section of the
slide rule (see Figure AN–1).
0
2
4
6
8
10
12
14
16
18
20 %
1.00
1.05
1.10
1.15
1.20
1.25
1.30
1.35 1.40 1.45 1.50 VWSR
80
75 70 65 60 55 50 45 40 35 30 25 20 15 10 5
0
.01 .02.03 .05 .10
.2 .3
.5 .7 1.0
2 3
5 7 10
20
50
100 %
30
SINGLE
RESISTIVE
DISCONTINUITY
ONLY
RETURN LOSS
(IMPULSE ONLY)
1.04 VSWR = 2% REFLECTION
20% = 1.5 VSWR
Figure D–1: Slide Rule of VSWR vs. Percent Reflected Voltage
On the upper scale, locate the known value of VSWR (or %). Adjacent to that point
is the corresponding value for % (or VSWR). VSWR is the peak-to-valley ratio of
standing sine waves.
NOTE
. The relationship between % holds only when the loss is a single impedance
discontinuity with negligible capacitive or inductive components (e.g., a 75
W
termination at the end of a 50
W
cable). The VSWR must be essentially the same for
all sine-wave frequencies.
Summary of Contents for 1503C
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Page 92: ...Appendix A Specifications A 6 1503C MTDR User Manual...
Page 104: ...Appendis B Operator Performance Checks B 12 1503C MTDR User Manual...
Page 122: ...Glossary Glossary 6 1503C MTDR User Manual...
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